Strange as it seems, Ali G Indahouse represents a first in British cinema. This rude, crude and cheeky film is our first genuinely homegrown 'gross-out' comedy, borrowing heavily from sharp-tongued, low-minded American movies, while maintaining a distinctly British voice.

Ali G, alias Sacha Baron Cohen, is by no means the first British TV character to get his own film. The tradition of small-to-big screen transfers runs from The Likely Lads to Porridge, from Are You Being Served? to The Boys in Blue (Cannon and Ball, lest we forget); British film history is littered with such efforts. These transfers were cheap and rarely troubled the box-office summits. In fact, The Monty Python films were unique in achieving both commercial and artistic success.

Even more recent efforts to carry TV success into the cinemas have had mixed fortunes - think of The Comic Strip films and Guest House Paradiso, Rik Mayall and Ade Edmonson's dire attempt to transfer the sensibilities of their Bottom television series. Mr Bean, it is true, made pots of money, but more important in our context is the success of Harry Enfield's Kevin and Perry Go Large, featuring the sullen teenagers in Ibiza. Although replete with poo jokes and exploding zits, it was rather tame for a gross-out comedy.

Ali G Indahouse - a genre-crossing, fish-out-of-water comedy about a 'black' man in a white world - doffs its cap (or whatever one calls that Hilfiger thing he wears) to far less sophisticated cinematic ancestors. And that's why it stands an excellent chance of cult success in America, something only the Pythons have ever managed.

The gags in Ali G have a lineage that runs from the 1978 high-school comedy Animal House to the Farrelly brothers (Dumb and Dumber, here's Something About Mary). The backfiring-scheme plot - in which the pot-smoking Ali is put forward as MP for Staines in a futile bid to undermine the Prime Minister - owes something to Mel Brooks' The Producers and Blazing Saddles .

Ali G's co-writer and producer, Dan Mazer, takes the comparisons as a compliment. 'It was the American films we grew up laughing at, not The Boys in Blue,' he says. 'As far as we were concerned, the Hollywood products were just funnier, gag for gag. When we set out, we just wanted to make something that made people laugh. We were ruthless in the edit - if there wasn't a gag in the scene, out it went.' Inevitably, a few jokes in the relentless onslaught do fall flat but then the accumulation of bad gags - and it takes some daring to be quite so bad - is in itself funny.

Mazer recently attended a test screening in America. 'I was expecting blank incomprehension,' he recalls. 'There was silence for some jokes about 'mingers' and girls being 'fit' but, other than that, they roared. Ali G to them is a quaint English guy who wants to be a gangsta, so the concept translates easily. In many senses, it's not an English film, because there wasn't an English model for us to follow.'

Sight and Sound critic Leslie Felperin was impressed: 'It was much better than I expected and I laughed hard and loud. I think it handles race and sexism very gently and carefully, almost with a sweet naïvety that takes the edge off the aspects of it you might feel uncomfortable with.'

Ali G probably stands closest comparison with Wayne's World, which broke out from a TV sketch into a worldwide hit. There are also parallels to be found in the feature-length cartoons of Beavis and Butthead and South Park, with whose (faux) naïvety Ali G has much in common.

Heat film editor Charles Gant believes the film is 'one of the best from the juvenile end of the film spectrum'. But, he adds, 'the film actually isn't as sophisticated as the act was on television. Because it's had to change formats and be scripted, it's lost some of the thrill of the improvised wit that made the character so famous.'

Although Ali G Indahouse can't boast the wit or slick plotting of There's Something About Mary, which remains the classic gross-out comedy, it will be a welcome distraction for British moviegoers. And, of course, the film's release will re-open the debate about whether Ali G's comedy is a commentary on black youth culture.

Ali G isn't trying to be black, says Mazer. 'He is a boy who's been infected by the export of American glamour, by its shine, glitter and attitudes, the stuff he's seen in movies and videos on MTV. He's devoured these messages and wishes/thinks his life should be like that, as cool as that. Whether he's black, Asian or white doesn't matter - the comedy is in the gap between his dream and his reality.'